During the fabrication of semiconductor devices, it is common to form electrical isolation regions upon the semiconductor substrate to isolate certain semiconductor devices from one another. Isolation of the semiconductors devices from one another reduces detrimental effects, such as, for example, parasitic effects and cross-talk effects. Typically, a local oxidation of silicon (LOCOS) technique is used, in conjunction with a nitride mask, to create isolation regions on a semiconductor substrate. As shown in FIG. 1A, a nitride mask 110 may be formed over a substrate 105 to leave an area 115 in which substrate 105 is exposed. A LOCOS oxidation technique may then be used, as shown in FIG. 1B, to create an oxide isolation region 120 in the substrate 105 in area 115. The isolation region 120 may include, for example, silicon dioxide (SiO2). As further shown in FIG. 1B, a conventional LOCOS technique produces “bird's beaks” 125 at the edges of the isolation region 120. Nitride mask 110 may bend upwards and the oxide of the isolation region 120 may substantially encroach beneath mask 110, thereby deforming nitride mask 110. Conventional LOCOS techniques, thus, lead to undesirable oxide encroachment beneath the mask 110.